1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method which have functions of receiving and printing image data.
2. Description of the Related Art
A pseudo-halftone technique is widely used for a printer and a multi-functional machine using ink or toner.
Using the pseudo-halftone technique has an advantage also in the aspect of image data size. In the multi-functional machine having a document box function, a document data size to be stored in a secondary storage unit, such as a hard disk, frequently requires a smaller capacity in the case of storing a binary image subjected to pseudo-halftone processing than in the case of storing a multi-bit multi-value image. Note that the document box function is a function of storing document data in a hard disk for performing sharing and distribution of the data. Further, the smaller data size has an advantage in the aspect of a network load in the case that image data is transmitted and received between the printers or the multi-functional machines connected with each other by a network.
In the case of storing the binary image data, however, the density characteristic of the image is determined at the time when the pseudo-halftone processing is performed, and there has not existed a method in which the density is adjusted afterward.
Japanese Patent Laid-Open No. 2000-83123 discloses a technique related to a binary image data transmission method in which a change in the density characteristic in print output is taken into consideration. This technique obtains a density correction characteristic of a receiving side device before image data is transmitted by a device which transmits the binary image data, and transmits the binary image data after performing the pseudo-halftone processing according to the density characteristic of the receiving side device.
However, even if the technique disclosed by Japanese Patent Laid-Open No. 2000-83123 is used, sometimes the output with the most suitable density is not performed at the time when the receiving side device carries out the print output. This is a case in which the output density characteristic changes because of an engine calibration or the like during a time between receiving and printing of the binary data in the receiving side device.
Further, even for a single printer or within a printing apparatus, there is a case in which a change of the density characteristic is desired afterward for the binary image subjected to the pseudo-half tone processing.
Depending on a configuration of the printing apparatus, a recording paper transfer speed sometimes changes for each paper feeder unit in the printing apparatus. This is a case when paper feed from a manual tray has a low speed while paper feed from a paper feed cassette has a high speed. The density characteristic of the printing apparatus sometimes changes depending on the paper transfer speed in the apparatus. Usually, when papers run out in the paper feed cassette during processing a job having a plurality of pages, for example, the same type paper in the manual tray is supplied by an automatic paper feed selection function, although the paper feed cassette is selected when the printing job processing is started. In this case, there arises a problem that the density characteristic changes during the job because of the difference in the paper transfer speeds.
Further, in the case that a plurality of printing apparatuses connected with each other by a network receives and transmits image data therebetween, the printing apparatuses can receive and transmit the image data therebetween by using a predetermined protocol and image format. Accordingly, the receiving side device can easily transfer the received image data to a third printing apparatus. In this case, the density characteristic is sometimes different between a device performing the pseudo-halftone processing to generate the binary image data and a device finally receiving the image data to print the binary image data.
An object of the present invention is to provide an image processing apparatus and an image processing method which print and output image data subjected to pseudo-halftone processing with an appropriate density characteristic.